Echocardiographic measurements as predictors of racing success

ABSTRACT

The present invention relates to methods for selecting racehorse candidates. Provided herein are methods for increasing the likelihood of selecting candidates that will be high earners, while reducing the likelihood of selecting candidates that will be low earners, on the basis of certain cardiac measurements.

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/414,962 (issued as U.S. Pat. No. 8,061,302), filed on Mar. 31, 2009,which is a continuation of U.S. patent application Ser. No. 10/521,087,filed on Jan. 13, 2005, which is a United States national stage entry ofInternational Application Serial No. PCT/US2003/019537, filed Jun. 20,2003, which in turn claims the priority benefit of U.S. ProvisionalApplication Ser. No. 60/396,592, filed Jul. 17, 2002. The disclosure ofeach of these prior applications is incorporated herein by reference inits entirety for all purposes.

FIELD OF THE INVENTION

The present invention is directed to methods for screening candidateracehorses, and improving the likelihood of selecting a candidate thatwill become a successful racehorse.

BACKGROUND

For centuries, perhaps ever since the horse was first domesticated,people have raced their horses against each other, to see which manowned the faster animal. Countless generations of breeding the fasteststallion to the best mares has led to the modern racehorse, amagnificent running machine, genetically selected to excel in the modernversion of “the sport of kings,” a sport that still thrives across theglobe today.

Since the sport first began, people have bought, sold and traded younghorses, with dreams of acquiring a horse that might one day mature intoa stakes winner. A huge business has developed around the breeding,preparation, and sale of potential racehorses. Potential buyers poreover sales catalogs, searching the horse's parentage and pedigree inhope of selecting a horse that contains just the right mix of speed,stamina, durability and temperament to grow into a successful racehorse.The racing candidate is carefully examined to make sure its legs arestraight, the airway is clear, and that there are no physical blemishesor infirmities that might diminish its chance of future success.“Experts,” sometimes boasting of years of experience at spotting futurechampions long before the horse ever sets foot on a racetrack, areregularly consulted to scrutinize the field of candidates, and help thewould-be owner select a horse that possess the right conformation, theright carriage, the right glint in the eye—the stuff of champions.

But despite all the statistical analysis of pedigree, the pre-salepoking and prodding, and the intense scrutiny of a countless number oftrained eyes, separating the future winners from the future losers hasremained an inexact science at best. In a study of all named (i.e.,registered) Thoroughbred foals born between 1985 and 1994, only about30% ever started a single race, and the average earnings per start ofall foals was only $1,378. Selecting the offspring of the top 1% ofstallions reduced the percentage of non-starters to about 15%, andincreased the average earnings per start to over $3,000, but still, alarge percentage of all young horses sold at auction fail to recouptheir original purchase price. One has only to look to the results ofthis year's Kentucky Derby to see how inaccurate the selection ofracehorse candidates can be: the race was won by Funny Cide, once a$75,000 purchase, while numerous horses from the same crop that sold formuch more, even ten or more times as much, failed to even win a singlemaiden race.

Accordingly, better methods for screening potential racehorse candidatesare needed, particularly methods that will increase the chances ofselecting a horse that is more likely to become a high earner, whiledecreasing the likelihood of selecting a horses that will turn out to bea low earner. The present invention is directed to these, as well asother ends.

SUMMARY OF THE INVENTION

It has now been discovered that certain objective measurements that maybe readily obtained from young horse racing candidates, e.g., heartand/or spleen size, may be used as predictors of the future racingsuccess. Accordingly, the present invention provides methods ofscreening a racehorse candidate and selecting a racehorse candidatelikely to become a high-earner racehorse.

The method for screening racehorse candidates includes the step ofobtaining one or more measurements, including echocardiographicmeasurements, from a racehorse candidate and comparing the measurementsto a collection of corresponding measurements from a group of horses. Inparticular, in one embodiment, the methods include the step of obtaininga measurement of the width of the ventricular septal wall of a racehorsecandidate and comparing it to ventricular septal wall width measurementsfrom a group of horses of similar age, sex, and weight. In anotherembodiment, the methods of the present invention further comprise thesteps of obtaining one or more measurements selected from thecross-sectional area of the left ventricle in diastole, thecross-sectional area of the left ventricle in systole, the body size(more specifically, the height×weight), or the splenic cross-sectionalarea of the candidate racehorse and comparing these additionalmeasurements to corresponding measurements from the group of horses.

In another embodiment of the present invention, the methods of thepresent invention include the step of obtaining a measurement of thesplenic cross-sectional area of a racehorse candidate and comparing itto splenic cross-sectional area measurements from the group of horses.In another embodiment, the methods of the present invention furthercomprise the steps of obtaining one or more measurements selected fromthe cross-sectional area of the left ventricle in diastole, thecross-sectional area of the left ventricle in systole, the body size, orthe interventricular septal wall width of the candidate racehorse andcomparing these additional measurements to corresponding measurementsfrom the group of horses.

After the measurements have been obtained from the candidate racehorse,the methods of the present invention may further include the step ofselecting a racehorse candidate if its ventricular septal wall widthmeasurement is greater than the mean ventricular septal wall width ofthe group of horses. In another embodiment, the methods of the presentinvention may further include the step of selecting a racehorsecandidate if one or more of its measurements, e.g., ventricular septalwall width, left ventricle cross sectional area in diastole or systole,body size, splenic cross sectional area, is greater than the meancorresponding measurement from the group of horses of similar age,weight and sex.

In yet another embodiment, the methods of the present invention mayfurther include the step of selecting a racehorse candidate if one ormore of its measurements, e.g., ventricular septal wall width, leftventricle cross sectional area in diastole or systole, body size,splenic cross sectional area, is in the 75^(th) percentile or higherwhen compared to corresponding measurements from the group of horses.The methods of the present invention may also include the step ofrejecting a racehorse candidate if one or more of its measurements,e.g., ventricular septal wall width, left ventricle cross sectional areain diastole or systole, body size, splenic cross sectional area, is notin the 75^(th) percentile or higher when compared to correspondingmeasurements from the group of horses.

In one aspect of the present invention, the measurements obtained fromthe horses are acquired using standard methods, commonly known andaccepted in the art. In another aspect, the ventricular septal wallwidth measurement is obtained by measuring a particular structure in anechocardiographic image of the heart, the measurement running from theattachment of the moderator band through the interventricular septuminto the right ventricle to the endocardial edge of the rightventricular free wall where the wall attaches to the interventricularseptum. In yet another embodiment, the left ventricle in diastole and/orsystole cross sectional area is obtained by measuring the circumferenceof the left ventricular chamber.

The methods of the present invention thus improve the odds of selectinghigh and excluding low earner racehorses. Additionally, from within thegroup of high earners, certain parameters may be applied that enable theselection of horses more likely to be high earners in races that extendbeyond a mile. These and other applications for the methods disclosedherein will be made apparent in the detailed description and examplesthat follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: A left parasternal short-axis echocardiogram of the leftventricle at peak systole from a 2-year-old Thoroughbred filly with aresting heart rate below 40 bpm obtained from the left cardiac windowwith a 3.5 MHz probe. The dotted line traces the endocardial border ofthe left ventricle at peak systole.

FIG. 2: A left parasternal short-axis echocardiogram of the leftventricle at end diastole from a 2-year-old Thoroughbred filly with aresting heart rate below 40 bpm obtained from the left cardiac windowwith a 3.5 MHz probe. The dotted line traces the endocardial border ofthe left ventricle at the end of diastole.

FIG. 3: A left parasternal short-axis echocardiogram of the leftventricle at end diastole from a 2-year-old Thoroughbred filly with aresting heart rate below 40 bpm obtained from the left cardiac windowwith a 3.5 MHz probe. The dotted line measures the attachment of themoderator band through the interventricular septum into the rightventricular to the endocardial edge of the right ventricular free wallwhere it attaches to the interventricular septum.

FIG. 4: LVD (mm²) measurements for colts and fillies at ages 12 to 28months.

FIG. 5: LVD (mm²) measurements for colts and fillies at weights of 850to 1150 pounds.

FIG. 6: LVS (mm²) measurements for colts and fillies at weights of 850to 1150 pounds.

FIG. 7: SW (mm) measurements for colts and fillies at weights of 850 to1150 pounds.

FIG. 8: PS (pct.) measurements for colts and fillies at weights of 850to 1150 pounds.

FIG. 9: Mean weight percentiles for high earner and low earner horses atages 12 to 28 months.

FIG. 10: Mean LVD percentiles for high earner and low earner horses atages 12 to 28 months.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides new methods for screening a racehorsecandidate. The present invention relates, in part, to the discovery thatcertain physical characteristics of the racehorse candidate that can bereadily measured may be used as a predictor of the horse's future racingability.

In particular, it has been found that certain echocardiographic featuresare correlated with racing success, and may be used to screen racehorsecandidates. Accordingly, the present invention provides, inter alia,methods of obtaining certain physical measurements of a candidateracehorse's heart.

The present invention also relates, in part, to the discovery that thesize of a horse's spleen can also be used as a predictor of the horse'sfuture racing ability. Accordingly, the present invention providesmethods of screening a racehorse candidate on the basis of its spleniccross-sectional area.

It has also been found that a horse's physical size for it'schronological age, particularly when viewed in combination with certaincardiac parameters or splenic cross sectional area, can be used topredict the racing ability of a candidate racehorse. Accordingly, thepresent invention provides screening methods that further include thestep of determining the physical size of a horse. For the purposes ofthe present invention, the physical size or body size of a horse or“HTWT” is determined by multiplying the height and the weight of thehorse. Methods of determining the height and weight of a horse are knownin the art, e.g., using a scale, weight tape, height stick, orwell-educated estimates based on visual inspection by those skilled inthe art.

In the methods of the present invention, the heart of a horse ismeasured in terms of one or more of the following variables: crosssectional area of the left ventricle in diastole (LVD), cross sectionalarea of the left ventricle in systole (LVS), ventricular septal wallwidth, and percent change in ventricular area per stroke (PS).

The term “ventricular septal wall width” refers to the width of theseptum dividing the right and left ventricles. A particularly preferredventricular septal wall measurement involves a particular cardiacstructure that runs from the endocardial edge of the right ventricularfree wall, at the point where the wall meets the interventricularseptum, through the interventricular septum, to the point of attachmentof the moderator band in the left ventricle, as shown for example inFIG. 3. This structure may be readily identified in a left parasternalshort-axis view, preferably obtained at end diastole, although otherviews may also be used to obtain measurements of this structure.Measurements of this particular structure are referred to herein as the“interventricular septal wall structural thickness” or “SW”.

The “cross-sectional area of the left ventricle in systole” or “LVS” ismeasured when the left ventricle contracts to its smallest size insystole. The “cross-sectional area of the left ventricle in diastole” or“LVD” is measured when the left ventricle expands to its largest size indiastole. These measurements can be obtained by any means known to thoseof ordinary skill in the art, for example, by using the “inner edge”method. In the “inner edge” method, linear parameters are measured fromthe inner edge of endocardial surfaces and areas are traced along theinner borders of the endocardial echoes. Thus, LVS and LVD may bedetermined by freezing, for example, a left parasternal short-axis twodimensional echocardiographic ultrasound image at the peak of systole,and the end of diastole, respectively, and tracing the internalperimeter of the left ventricular chamber using calipers on theultrasound machine. The area inside the tracing is then calculated basedon a pixel count (512×512 for total screen). Many commercially availablediagnostic ultrasound machines include software capable of measuring acircumscribed area in this fashion.

Alternatively, the cardiac measurements cited herein may be measured byany method known to those of skill in the art, as may be described, forexample, in one or more of the following: Voros et al., (1990) EquineVet. J. p. 392-397; Weyman, A. E. (1982) Cross-sectionalechocardiography, Lea & Febiger, Philadelphia, p. 497-504; Wyatt, et al.(1979) Circulation 60, p. 1104-1113; O'Grady et al. (1986) Vet. Radiol.27, p. 34-49; Henry, W. L., et al. (1980) Circulation 62, p. 212-217;Feigenbaum, H. (1986) Echocardiography, 4th edn. Lea & Febiger,Philadelphia; Voros, et al, Equine vet. J. p. 398-402; Young, L. E., andScott, G. R. (1998) Equine vet. J. 30 (2) p. 117-122; Slater, J. D. andHerrtage, M. E. (1995), Equine vet. J., Suppl. 19, p. 28-32; Marr, etal., Equine vet. J., Suppl. 30, p. 131-136; Young et al., (1998), Equinevet. J. 30 (2) p. 117-122; Young, L. E. (1999) Equine vet. J., Suppl.30, p. 195-198; Pascoe, J. R., et al., (1990) Equine vet. J., Suppl. 30,p. 148-152.

The “percent change in ventricular area per stroke” or “PS” is computedby subtracting LVS from LVD, dividing the resultant number by LVD andmultiplying by 100, e.g.,

${PS} = {\frac{{LVD} - {LVS}}{LVD} \times 100.}$

Thus, PS may be correlated with the volume of blood that is ejected fromthe heart per stroke, at rest.

In the methods of the present invention, the splenic cross sectionalarea or “SPLN” is obtained by producing a cross sectional image of thehorse's spleen, and determining the cross sectional area of same, asdiscussed above with regard to the LVD and LVS measurements.

In one embodiment of the present invention, LVS, LVD, and SW aremeasured from a left parasternal short axis echocardiogram of the leftventricle of the horse at end systole and end diastole. Theechocardiogram can be obtained from the left cardiac window using a 3.5MHz probe. During the electrocardiographic exam, the ultrasoundtransducer can be held in the right hand with the cursor facingcaudally. The left forelimb can be advanced slightly and the transducercan be placed in the 4th or 5th left intercostal space, at a level justdorsal to the point of the olecranon. The transducer beam can bedirected perpendicular (horizontal) to the longitudinal cardiac axis.The resulting image provides a nearly circular appearance to the leftventricular lumen. Moving (angling) the transducer beam from the apex tothe base of the heart, the moderator band(s), papillary muscle, chordaetendinae and septal leaf of the mitral valve can be identified and usedas intracardiac reference points to obtain reproducible cardiac imagesin the same tomographic plane. In other embodiments of the presentinvention, alternate echocardiogram views may be obtained and thecardiac and splenic size measured from the alternate views, e.g., rightparasternal short axis view, left or right parasternal long axis view,apical views. Typically three to five cardiac cycles are measured foreach echocardiographic measurement. This helps minimize error, forexample, in the timing of peak systole, and end diastole. Short axisimages can be projected according to international terminology based onthe recommendations of the American Society of Echocardiography (Henry1980, supra; Feigenbaum 1986, supra). Short axis images recorded fromthe left side of the chest can be projected as though the tomographicplanes are viewed from the base to the apex of the heart.

The accuracy of the measurements may be compromised when a horse's heartis beating very quickly. For example, in a very rapidly beating heart,it may be difficult to accurately freeze the image at peak systole, orat end diastole. Accordingly, it is preferred that the measurements betaken when the horse's resting heart rate is less than about 50 beatsper minute, with a resting heart rate at the time of examination of lessthan about 40 beats per minute being even more preferred.

The present invention also provides a collection of measurements from agroup of horses for comparison with those obtained from the candidateracehorse. In order to create a collection or database of horsemeasurements, selected measurements are obtained from a group of horses,as discussed above. The database preferably includes measurements ofeach of the variables LVD, LVS, PS, HTWT, SPLN, and ventricular septalwall width, particularly the variable SW, as defined above. Of course,obtaining measurements from a large number of individuals will minimizestatistical aberrations, and therefore improve the predictive accuracyof the methods disclosed herein. Typically, the group of horses includesat least about 1000 individuals, with a group of greater than 5000horses being preferred. Even more preferably, the database will includemeasurements of at least about 7500 individuals.

Since most racehorse candidates are sold as yearlings or two-year olds,it is preferred that the individuals making up the group of horses rangein age from about 12 months to about 28 months of age chronologically.It has been found, however, that cardiac measurements vary, depending onage, sex, and weight, making it difficult to compare horses on the basisof cardiac measurements alone, without adjusting for the effects ofthese parameters. Accordingly, an adequate comparative sample of horsesof about the same age, sex and weight as the racehorse candidate ispreferred. Preferably, the group of horses used for the comparison areof the same breed as the racehorse candidate, and that breed ispreferably Thoroughbred. As used herein, the term “about the same age,sex and weight” means that the individuals making up the collection ofhorses used for comparative purposes have a date of birth within about30 days of the racing candidate, are of the same genetic gender, andhave a weight of within about 25 pounds of the racing candidate.Preferably, the database will include cardiac measurements of at leastabout 35 horses of the same age, sex and weight as the racehorsecandidate. More preferably, the cardiac measurements of the candidateracehorse are compared to a database that includes cardiac measurementsof at least about 75, and even more preferably at least about 150, andstill more preferably, at least about 300 horses of the same age, sexand weight as the racehorse candidate. As a result of such a largestatistical sample, greater accuracy and predictive ability may beachieved by the methods described herein.

Once a database of sufficient size has been generated to assure astatistically significant number of horses of about the same age, sexand weight as the racehorse candidate have been obtained, a comparisoncan be readily made. For example, the candidate and each horse in thegroup may be ranked according to each measurement on a scale from 0 to100. Percentiles for each measurement may then be calculated using thefollowing equation:

$\frac{R - 0.5}{N},$

wherein R equals rank and N equals the number of horses. For example, ifthere are 100 colts of similar age and weight, and one colt has the93^(rd) largest LVD, he would have an LVD percentile of 92.5%.

$\frac{93.0 - 0.5}{100} = {92.5{\%.}}$

By reporting the measurements in terms of percentiles, determinedrelative to other horses of the same sex, age (within 30 days) andweight (within 25 pounds), the cardiac measurements become independentof a horse's age, sex and weight. Thus, the racehorse candidate may beassigned a percentile rank for each measurement variable, e.g., LVD,LVS, SW, SPLN, HTWT, and/or PS, as compared to a statisticallysignificant sample of horses of about the same age, sex and weight.

Other methods for assigning a relative rank to the racing candidate areknown to those of skill in the art, and may be used as an alternative tothe percentile system described above. For example, standardized scoresmay be obtained, wherein the standardized score for each horse in thegroup is determined by subtracting the mean measurement for the groupfrom the observed measurement of an individual horse, and dividing theresult by the standard deviation for that variable for the group. Suchalternative methods should be considered to merely be variants of thepercentile method described above, and do not represent alternativeembodiments of the instant invention.

This comparison can be used to predict the racing ability of thecandidate racehorse, e.g., whether the candidate racehorse will be morelikely to become a high earner or lower earner. For example, asdescribed more fully in the examples to follow, by selecting a racehorsecandidate having a ventricular septal wall width greater than the meanventricular septal wall width of a group of horses of about the sameage, sex and weight, and/or rejecting a racehorse candidate that has aseptal wall width less than the mean, the likelihood of selecting a highearner racehorse is significantly improved. The odds of selecting a highearner racehorse are further improved by selecting a racehorse candidatethat has a ventricular septal wall width that is in the 75^(th)percentile or higher, and/or rejecting a candidate that has a septalwall width that is lower than the 75^(th) percentile. Conversely, theodds of selecting a low earner are decreased by selecting a horse thathas a ventricular septal wall width greater than the mean ventricularseptal wall width of a group of horses of about the same age, sex andweight, with the odds of selecting a low earner even further reduced byselecting a racehorse candidate that has a ventricular septal wall widththat is in the 75^(th) percentile or higher.

Similarly, by selecting racehorse candidates on the basis ofmeasurements for other variables and/or combinations of variablesdiscussed herein, including LVD, LVS, SPLN, HTWT, SW and PS, thelikelihood of selecting a candidate that will be a high earner may beincreased, and the likelihood of selecting a candidate that will be alow earner will be reduced. Thus, certain embodiments of the presentinvention are directed to methods that comprise selecting horses thatexhibit one or more of the aforementioned measurements greater than themean measurement, and preferably fall in the 75^(th) percentile orhigher, than is seen in a group of horses of about the same age, sex andweight.

Additionally, as discussed in more detail in the examples to follow,using the methods of the present invention, in addition to increasingthe likelihood of identifying a racehorse candidate that will be afuture high earner racehorse, the methods of the present invention canalso be used to increase the likelihood of selecting a horse that willbe a high earner router, as opposed to a high earner sprinter. As usedherein, a “sprint” is a race of 1 mile (8 furlongs) or less, while a“route” race is one of at least about 8.5 furlongs. Since the majorityof graded stakes races for Thoroughbred horses in both the United Statesand Europe (i.e., the races with the highest purses) are contested atdistances of greater than 1 mile, it may be advantageous to select aracehorse candidate with an increased likelihood of being a high earnerrouter.

Moreover, after conducting measurements on over 7000 Thoroughbredyearling and two-year old racing candidates, and subsequently followingtheir racing careers (as discussed more fully in the examples to follow)it has been found that extremely high earners, i.e. horses that earnedat least $250,000 by the end of their three-year old year, were aboutthree times more likely to have above average HTWT and LVD measurements,when compared to a group of horses of about the same age, sex andweight, than to have below average HTWT and LVD measurements.Accordingly, these variables may be used in the methods of the presentinvention to increase the likelihood of selecting a racehorse candidatethat will be an extremely high earner.

The present invention also provides methods for maintaining a horseregistry system or database. Such a system can be managed usingbioinformatics. Bioinformatics is the study and application of computerand statistical techniques to the management of biological information.Thus, in one embodiment, the present invention provides a method forpopulating a database with the biological information obtained using themethods of the present invention. For example, a database can bepopulated with LVD, LVS, PS, HTWT, SPLN and ventricular septal wallwidth measurements from a group of horses whose racing abilities areknown. Once a database of sufficient size has been generated, the racingability of racehorse candidates can be predicted as described above,e.g., by comparing measurements from racehorse candidates tocorresponding measurements from a group of horses of about the same age,sex, and weight and ranking the horses according to each measurement.Measurements from the racehorse candidates can be optionally enteredinto the database as well.

In another embodiment, the present invention also provides an apparatusfor automating the methods of the present invention, the apparatuscomprising a computer and a software system capable of comparing andstandardizing echocardiographic and other measurements from horses. Thedata is inputted in computer-readable form and stored incomputer-retrievable format. The present invention also providescomputer-readable medium encoded with a data set comprising profiles,e.g., LVD, LVS, PS, HTWT, SPLN, and ventricular septal wall widthmeasurements, of horses known to be high earners, low earners, highearner routers, or high earner sprinters. The information in the dataset can be used for comparison purposes in order to improve one's oddsof selecting a higher earner racehorse. It can also be used byhandicappers or others in order to evaluate horses for betting purposes.

The methods described herein for obtaining certain measurements fromhorses provides information which can be used to determine the racingability of candidate racehorses. Although the data generated from themethods of this invention is suited for manual review and analysis, in apreferred embodiment, prior data processing using high-speed computersis utilized.

The invention also provides for the storage and retrieval of acollection of profiles and comparisons in a computer data storageapparatus, which can include magnetic disks, optical disks,magneto-optical disks, DRAM, SRAM, SGRAM, SDRAM, RDRAM, DDR RAM,magnetic bubble memory devices, and other data storage devices,including CPU registers and on-CPU data storage arrays.

This invention also preferably provides a magnetic disk, such as anIBM-compatible (DOS, Windows, Windows 95/98/2000, Windows NT, OS/2,etc.) or other format, e.g., Linux, SunOS, Solaris, AIX, SCO, Unix, VMS,MV, Mactinosh etc., floppy diskette or hard (fixed, Winchester) diskdrive, comprising a bit pattern encoding data collected from the methodsof the present invention in a file format suitable for retrievable andprocessing in a computerized comparison or relative quantificationmethod.

The invention also provides a network, comprising a plurality ofcomputing devices linked via a data link, such as an Ethernet cable(coax or 10BaseT), telephone line, ISDN line, wireless network, opticalfiber, or other suitable signal transmission medium, whereby at leastone network device comprises a pattern of magnetic domains and/or chargedomains comprising a bit pattern encoding data acquired from the methodsof the invention.

The invention also provides a method for transmitting data that includesgenerating an electronic signal on an electronic communications device,such as a modem, ISDN terminal adapter, DSL, cable modem, ATM switch, orthe like, wherein the signal includes (in native or encrypted format) abit pattern encoding data collected using the methods of the presentinvention.

In a preferred embodiment, the invention provides a computer system forperforming the methods of the present invention. A central processor ispreferably initialized to load and execute the computer program foralignment and/or comparison of results. Data is entered into the centralprocessor via an I/O device. Execution of the computer program resultsin the central processor retrieving the data from the data file.

The target data or record and the computer program can be transferred tosecondary memory, which is typically random access memory. For example,a central processor can be a conventional computer; a program can be acommercial or public domain molecular biology software package; a datafile can be an optical or magnetic disk, a data server, or a memorydevice; an I/O device can be a terminal comprising a video display and akeyboard, a modem, an ISDN terminal adapter, an Ethernet port, a punchedcard reader, a magnetic strip reader, or other suitable I/O device.

The invention also provides the use of a computer system, such as thatdescribed above, which comprises: (1) a computer; (2) a stored bitpattern encoding a collection of measurements obtained by the methods ofthe present invention, which may be stored in the computer; (3) acomparison control; and (4) a program for comparison.

All publications and patent documents cited above are herebyincorporated by reference in their entirety for all purposes to the sameextent as if each were so individually denoted.

The below examples are non-limiting and for illustrating the presentinvention. Alternatives and variations of the below examples within thescope of the present invention as per the below claims may be carriedout by a person skilled in the art.

EXAMPLES Example 1 Selecting the Group of Horses

Selected two dimensional echocardiographic (2DE) measurements wererecorded for 5,431 yearling and 2,003 two-year-old Thoroughbredracehorses between the ages of 12 through 28 months. These were unique,unraced horses. Cardiac measurements were recorded primarily at selectpublic yearling and two-year-old auctions between 1995 and 2000.

All descriptive statistics used only the most current 2DE measurementsfrom each horse, in order to prevent multiple measurements of the samehorse from overly influencing statistics within small groups of horses.Using the most recent measurement of the same horse also maximized thenumber of two-year-olds available for the study. Among the 7,434 uniquehorses, there were 2,940 fillies (40%), 4,494 colts (60%), 5,431yearlings (73%), and 2,003 two-year-olds (27%).

Additionally, 5,909 horses (79%) were at least three years of age by 1Jan. 2000. Among these horses, by the end of their three-year-old year,1,156 (20%) raced outside of North America (foreign) and 4,753 (80%)stayed in North American. Among the North American horses, 1,073 (23%)never raced and 3,680 (77%) started at least once (see Table 1).

TABLE 1 Number of Races through Three-Year-Old Year Among HorsesCategorized as North American Number of Races Number Percent through ofof Cumulative 3-Year-Old Year Horses Total Percentage Unraced 1,07322.58 22.58 1-5 1,274 26.80 49.38  6-10 1,215 25.56 74.94 11-15 78416.50 91.44 16-20 297 6.25 97.69 21-25 95 2.00 99.69 26-30 13 0.27 99.9631-35 1 0.02 99.98 36-40 1 0.02 100.00 Total 4,753 100.00 100.00

Data from horses with resting heart rates above 40 beats per minute wasexcluded from this study. The same technician, ultrasound equipment andmeasurement protocol, as described in the materials and methods sectionof this paper, was used for all horses studied. Comments regardingphysical appearance, body condition, and conformation were recordedduring each examination. Table 2, below, provides some perspective tothe figures in Table 1.

TABLE 2 Averages for the Breed Worldwide Performances of NamedThoroughbred Foals Born in North America between 1985-1994 (Source:Thoroughbred Times, Jun. 8, 2002, p. 31) Foals by Foals of Top 1% Subsetof Population 1985-1994 of Sires % Starters/foals 68.9% 84.8% % Stakeswinners/foals 3.2% 9.1% % Graded stakes winners/foals 0.7% 3.6% % Grade1 stakes winners/foals 0.2% 1.2% % 2-year-old starters/foals 33.5% 46.2%% 3-year-old starters/foals 59.0% 76.6% % 4-year-old starters/foals44.0% 57.1% % 5-year-old and up starters/foals 26.5% 36.9% Averagecareer starts/foal 14.5 18.7 Average career starts/starter 21.1 22.0Average win distance in furlongs 6.82 7.24 Average earnings/starter$29,102 $71,349 Average earnings/start $1,378 $3,242 Note: Top 1% ofsires determined by total progeny earnings for 1985-1994.

TABLE 3 Sale to Racetrack Performance of 1990-1999 Graduates of MajorYearling Sales (Source: Thoroughbred Times, Jul. 6, 2002, p. 20) Pct.SELECT YEARLING No. Median Starts Starts Pct. Graded Avg. AUCTION NAME &Horses Sale Avg. Per Per Pct. Stakes Stakes Win LOCATION Sold PriceEarnings Starters (%) Starter Foal Wnrs. Wnrs. Wnrs. Dist. Fasig-TiptonKentucky - July 1,792 $35,000 $61,132  1,577 (88.0%) 19.2 16.9 68.5%6.9% 2.7% 6.99 Keeneland Kentucky - July 1,945 235,000 112,752  1,672(86.0%) 14.7 12.7 62.1% 11.3% 6.3% 7.91 Keeneland Kentucky - September28,176 22,000 48,768 24,130 (85.6%) 20.0 17.1 64.9% 6.4% 2.0% 7.01Fasig-Tipton Saratoga - August 1,535 105,000 78,696  1,338 (87.2%) 16.814.7 65.8% 10.0% 4.5% 7.53

TABLE 4 Averages Among Horses in this Study Statistics through theThree-Year-Old Year of Study Horses Horses not Known to have RacedOutside of North America All Horses Subset of Study Population in thisStudy % Stakes winners 6.25% % Graded stakes winners 2.90% % Grade 1stakes winners 1.09% % At Least Stakes Placed (including winners) 12.57%% At Least Graded Stakes Placed (including winners) 5.14% % At LeastGrade I Stales Placed (including winners) 1.48% Note: Includes unracedhorses. Race dollar amounts earned can be compared between horseswithout currency or country distortions. Compare percentages in thistable to those of the top 1% of sires' progeny, shown in Table 2.

Performance records. All horses used to predict performance had racerecords through their three-year-old year. Race records included racedate, racetrack, race number, distance raced, level of race, claimingprice, finish position and earnings. Horses that raced outside of NorthAmerica were identified as “foreign,” and their race records were notused, since they were often incomplete or difficult to compare withNorth American records on the basis of dollar value or race level.

Sample Bias. There were pedigree and conformation biases, since thehorses examined at “select” public auctions were pre-selected by auctioncompanies based on above-average commercial assessment of pedigree andconformation. Not all horses at each auction were measured, nor weresubjects randomly selected. Horses were further pre-selected horses forcardiac measurement based on additional criteria.

Pre-selection biases were reflected in the percentage of stakes winnersamong horses measured. For example, midway through the 1990 foal crop'sten-year-old year, 2.3 percent had won a stakes race (ThoroughbredTimes, Jul. 22, 2000, p. 51). In contrast, 6.7 percent of horsesmeasured for this study, and which were not known to have raced outsideof North America, won a stakes race before they were four years old.

Example 2 Measurement Equipment and Techniques

A Pie Medical, digital cineloop scanner 200 from Classic Medical,(Tequesta, Fla.), with a 3.5 MHz annular array, multiring crystaltransducer with a 30-cm field of view at 22 frames per second was usedfor all measurements. The depth of display varied from 15 to 25centimeters depending on the size of the horse. The ultrasound recorderwas equipped with electronic calipers that were used to measure thestored images at the time of the examination.

SAS release 6.12 (SAS Institute, Cary, N.C.), for Windows NT (Microsoft)was used for statistical analysis. Universe (IBM) for Windows 2000(Microsoft) was used to manage the data. The server was a Dell 2300Poweredge (Dell, Atlanta, Ga.) with dual 450 MHz Intel Pentiumprocessors, running Windows 2000.

The 2DE imaging protocol was carried out on all horses, by the same,experienced (>5 years) technician to reduce measurement variability.Acoustical coupling gel (Aquasonic 100 ultrasound transmissiongel—Parker, Fairfield, N.J.) was applied liberally over the girth areain the 4th and 5th intercostal spaces, starting just below the level ofthe point of the shoulder down to the level of the olecranon. Three tofive cardiac cycles were measured for each variable. Measurements werenot made if the heart rate exceeded 40 beats/min., if the heart rhythmwas irregular, or if the images were unclear.

During 2DE examination, the ultrasound transducer was held in the righthand with the cursor facing caudally. The left forelimb was advancedslightly and the transducer was placed in the 4th or 5th leftintercostal space, at a level just dorsal to the point of the olecranon.From this position, a left parasternal short axis view could be obtainedby directing the transducer beam perpendicular (horizontal) to thelongitudinal cardiac axis. The image provided a nearly circularappearance to the left ventricular lumen. Moving (angling) thetransducer beam from the apex to the base of the heart, the moderatorband(s), papillary muscle, chordae tendinae and septal leaf of themitral valve were identified and then used as intracardiac referencepoints to obtain reproducible cardiac images in the same tomographicplane.

Except where noted, the short axis images were projected according tointernational terminology based on the recommendations of the AmericanSociety of Echocardiography (Henry 1980, Feigenbaum 1986). Short axisimages recorded from the left side of the chest were projected as thoughthe tomographic planes were viewed from the base to the apex of theheart.

The 2DE measurements recorded for all 7,434 horses were measured usingelectronic calipers. For all dimensions, the “inner edge” method wasused (Wyatt et al 1979, Weyman 1982, O'Grady, Bonagura, Powers andHerring 1986), i.e., linear parameters were measured from the inner edgeof endocardial surfaces, and areas were traced along the inner bordersof the endocardial echoes.

The following variables, as shown and described in FIGS. 1-3, weremeasured from the stored images: Left ventricular cross sectional areain diastole (LVD); left ventricular cross sectional area in systole(LVS); interventricular septal wall structural thickness in diastole(SW). Percent stroke volume (PS) was computed using the formula:

${PS} = {\frac{{LVD} - {LVS}}{LVD} \times 100}$

The ultrasound technician estimated HEIGHT and WEIGHT based solely onvisual inspection and prior experience. The variable HTWT, which was theproduct of height times weight, was used in this research as an estimateof overall body size. The ultrasound technician, a life-longhorseperson, trained horses prior to this research. While a trainer, shehad an on-site horse scale in a 40-stall training facility and tookdaily weight measurements of horses, and compared scale results toweight tape measurements. Alternatively, a five rating category systemwas used to describe height and weight. For example, the horses weredivided on the basis of weight or height into the following fivecategories: well below average (at least 1.0 standard deviation belowthe mean), below average (from 0.5 to 1.0 standard deviations below themean), average (within 0.5 standard deviations of the mean), aboveaverage (from 0.5 to 1.0 standard deviations above the mean), and wellabove average (at least 1.0 standard deviation above the mean).

Each weight and height measurement was assigned a whole number from 1 to5, with 1 equal to “well below average” and 5 equal to “well aboveaverage.” HTPLUSWT was created as the sum of these weight and heightratings, providing an overall physical size estimate. Each horse'scardiac measurements (i.e., LVD, LVS, SW, and PS) were ranked (expressedas a percentile ranging from 0 to 100) relative to those of other horsesof the same sex, chronological age, and of the same 1-5 weight group.Stepwise and discriminant results based on the 1-5 weight categorieswere similar to those results based on estimation of pounds.

Most cardiac measurements varied depending upon age, sex and weight,making it extremely difficult to compare horses on the basis of cardiacmeasurements without simultaneously adjusting for the effects of theseparameters. Two statistical techniques, percentiles and standardizedscores, eliminated the effects of age, sex and weight. These statisticaltechniques were only possible due to the large number of horses studied.Percentiles and standardized scores for LVD, LVS, SW, and PS werecalculated by comparing the subject horse to others that were:

-   -   The same sex as the subject horse    -   Measured within 30 days of chronological age of the subject        horse    -   Measured within 1 year of when the subject horse was measured    -   Within 25 pounds of weight of the subject horse

Percentiles and standardized scores for WEIGHT, HEIGHT and HTWT (HTWT isthe product of height times weight) were calculated as above, exceptwithout weight restrictions on the comparison group.

Subject comparisons were limited to within +1 year of the measurementdate in order to minimize the possible effects of gradual small changesin calibration, methodology and external variables acting on thesubjects. Examples of external variables that may have changed over timeand affected measurements include sales preparation techniques of horsesat auctions, steroid use, growth hormones, wear and tear on equipment,etc.

Technically, percentiles fail to maintain initial distances betweenvariables. Since most data in natural, biological phenomena is locatednear the middle of the Gaussian-shaped distribution, measurements in the50^(th) and 52^(nd) percentiles are closer in absolute value than thosein the 95^(th) and 97^(th) percentiles. Standardized scores describedbelow maintain the natural spacing between variables, producing ascale-free statistic with a mean of 0, and a standard deviation of 1.

${{Standardized}\mspace{14mu} {Score}} = \frac{{Observation} - {Mean}}{{Standard}\mspace{14mu} {Deviation}}$

Standardized scores could be difficult to interpret because, while theygenerally ranged from −3 to +3, they tended to congregate around zero.It seems easier to understand that a horse is in the 70^(th) percentilecompared to his peers than to know that his standardized score is 0.55.

Statistical analyses and tables in this text are based on percentiles.The same analyses and tables in terms of standardized scores producedvirtually the same results (data not shown).

Example 3 Reproducibility and Sources of Measurement Variability

Variation (or differences) between cardiac measurements is caused by acombination of within- and between-subject variation. Within-subjectvariation, sometimes called measurement error, indicates how accuratelyor reproducibly the technician and equipment measures a given variable(hearts and horses are moving targets). Between-subject variation is therange of expected differences among a particular variable in the generalpopulation that isn't due to error. Between-subject variation accountedfor 84-92% of variation in cardiac measurements in this study, whilewithin-subject variation accounted for 8-16% of variation.

Measurement variability was calculated for LVD, LVS, and SW among 1,464horses measured in 1999. These cardiac measurements were repeated atleast three times within a period of a few minutes. [1,571 horses weremeasured in 1999. Those excluded from this variability study lacked atleast three measurements for LVD, LVS, or SW because of auctionconditions, during which the technician may have lacked time to repeatmeasurements, could not sustain a resting heart rate (or behavioralcooperation), or reported only the average.]

Table 5 summarizes between-subject variation (s_(B)) and within-subjectvariation (s_(W)) and shows some basic statistical equations used.Column 1 lists the variables studied. Column 2 lists the mean value ofeach variable among all 1,464 horses in this part of the study. Column 3lists between-subject variation, which is the standard deviationassociated with the mean reported in Column 2 Column 4 listswithin-subject variation. Column 5 lists total variation. Column 6 liststhe percentage of total variation due to within-subject variation (ormeasurement error). S_(B) ² and S_(W) ², as used in the equations, aremean squared error terms from the between- and within-subject groupsstudied.

TABLE 5 Summary of Measurement Variability for Combined Sexes (LVD andLVS units = mm², SW units = mm)

ℑ

⊕ Variable Population Mean (n = 1,464) Between- Subject Variation{square root over (s_(B) ²)} Within-Subject Variation {square root over(s_(W) ²)} Total Variation {square root over (s_(W) ² + s_(B) ²)} Pct.of Variation due to Within- Subject Variation$\frac{s_{W}^{2}}{s_{W}^{2} + s_{B}^{2}} \times 100$ LVD 13,282 1,490424 1,549 7.50% LVS 4,329 496 215 540 15.81% SW 55.5 4.54 1.98 4.9615.97%

The within-subject variations listed in Table 5 were used to computeconfidence intervals as reported in Table 6, and to answer the followingquestions:

(1) How accurately did a single cardiac measurement (i.e., not anaverage of measurements repeated over a period of a few minutes)describe the true value? A statistical solution is to use the “95%confidence interval for a single measurement,” as shown in Column 2 ofTable 6. In this example, the value was 831 mm² for LVD. This means thatthere is a 95% probability that the true LVD lies within 831 mm² of asingle LVD measurement.

(2) How accurately did the mean of three repeated cardiac measurementsover the course of a few minutes describe the true value? A statisticalsolution is to utilize the “95% confidence interval for repeatedmeasurements,” as shown in Column 3 of Table 6. For example, this valuewas 480 mm² for LVD. This means that there is a 95% probability that thetrue LVD is within 480 mm² of the mean of three repeated LVDmeasurements.

(3) How much of a difference between cardiac measurements over someperiod of time would rule out measurement error as the sole source ofthe difference? A statistical solution is to use the “95% confidenceinterval for repeated measurements from two separate dates,” as shown inColumn 4 of Table 6. For example, this value was 679 mm² for LVD. Thismeans that if the difference between LVD measurements on different datesexceeded 679, then there is a 95% probability that measurement error wasnot the sole source of that difference.

(4) How much of a difference between repeated cardiac measurements oftwo different horses would rule out measurement error as the sole sourceof the difference? A conservative statistical solution is to use the 95%confidence interval just mentioned, as listed in Column 4 of Table 6.For example, this value was 679 mm² for LVD. This means that if thedifference between horses' LVDs exceeded 679 mm², then there is a 95%probability that measurement error was not the sole source of thatdifference.

TABLE 6 95% Confidence Intervals (C.I.) Associated with Within-SubjectVariations Reported in Table 5 (LVD and LVS units = mm², SW units = mm)

ℑ

Variable 95% C.I. for a Single Measurement$1.96\mspace{14mu} \bullet \mspace{14mu} \sqrt{S_{W}^{2}}$ 95% C.I.for a Measurement Repeated 3 Times Over the Course of a Few Minutes (n =3) $\frac{1.96 \cdot \sqrt{s_{w}^{2}}}{\sqrt{n}}$ 95% C.I. for a HorseMeasured on 2 Separate Dates or for Measurements of 2 Different Horses(n = 3) $\frac{1.96 \cdot \sqrt{2} \cdot \sqrt{s_{w}^{2}}}{\sqrt{n}}$LVD 831 480 679 LVS 421 243 344 SW 3.9 2.3 3.2

The average percent change in cardiac measurements for horses measuredtwice within the same month of age was calculated for horses 14-17months of age. These were the only individual months of age with atleast five different horses represented.

The change in the cardiac measurements of these horses fell within therange of expected measurement error described in Table 5. Most changewas positive, indicating that growth may have occurred in addition tomeasurement variation. Measurement variation among horses measured twicewithin the same month was also influenced by other factors, e.g., somehorses were re-measured because the ultrasound technician wasn'tsatisfied with the initial measurement, likely due to the horse'sbehavior (i.e., suspected illness, medications, or elevated heart rateafter start of exam).

Example 4 Statistical Overview of Cardiac Data—Descriptive Statistics

Means and standard deviations of cardiac raw data for combined sexes arepresented in Table 7-Table 8 by months of age.

TABLE 7 Means of Cardiac Measurements for Combined Sexes - by Months ofAge (Total n = 7,434) Number Cardiac Measurement Means Months of Age LVDLVS SW PS WEIGHT HEIGHT of Age Horses SPLN (months) (mm²) (mm²) (mm)(pct.) (lbs.) (hands) 12 81 171 12.5 11,534 3,823 49.4 66.82 801 14.5213 155 174 13.5 12,025 3,982 50.7 66.86 875 14.87 14 399 175 14.6 12,3624,038 50.9 67.32 944 15.12 15 758 176 15.6 12,395 4,024 51.1 67.52 97015.26 16 1,279 178 16.5 12,689 4,133 51.9 67.41 986 15.37 17 1,196 18217.5 12,843 4,182 52.4 67.41 996 15.42 18 856 179 18.5 12,948 4,203 52.467.52 1,001 15.47 19 551 186 19.4 13,285 4,330 53.5 67.36 1,005 15.51 20248 190 20.5 13,504 4,431 53.9 67.16 1,013 15.59 21 337 196 21.5 13,4284,344 54.0 67.64 1,016 15.60 22 440 201 22.5 13,633 4,411 54.7 67.641,026 15.64 23 485 200 23.5 13,706 4,384 54.7 68.04 1,032 15.69 24 333198 24.5 13,646 4,413 54.6 67.65 1,036 15.65 25 184 201 25.4 13,8034,409 55.2 68.08 1,046 15.77 26 95 199 26.5 13,657 4,420 54.6 67.661,045 15.77 27 37 215 27.3 13,638 4,415 55.1 67.65 1,036 15.75

TABLE 8 Standard Deviations of Cardiac Measurements for Combined Sexes -by Months of Age Corresponding to Means shown in Table 7 (Total n =7,434) Number Cardiac Measurement Standard Deviations Months of Age LVDLVS SW PS WEIGHT HEIGHT of Age Horses SPLN (months) (mm²) (mm²) (mm)(pct.) (lbs.) (hands) 12 81 26.8 0.2791 1,232 424 4.09 1.989 116.2 0.59213 155 28.3 0.2924 1,392 505 4.46 2.206 104.6 0.493 14 399 33.4 0.28971,408 519 5.12 2.329 73.9 0.394 15 758 34.1 0.2840 1,548 553 5.16 2.22359.6 0.357 16 1,279 36.5 0.2841 1,567 560 5.50 2.297 50.9 0.355 17 1,19638.1 0.2902 1,541 551 5.29 2.328 49.4 0.369 18 856 37.4 0.2783 1,595 5815.45 2.470 50.1 0.368 19 551 39.5 0.2800 1,504 526 5.24 2.278 49.4 0.36720 248 38.9 0.2898 1,347 494 4.34 2.204 45.8 0.358 21 337 45.7 0.29081,459 545 4.84 2.239 46.1 0.367 22 440 46.1 0.2760 1,404 547 4.59 2.28341.7 0.354 23 485 44.3 0.2889 1,366 554 4.56 2.202 44.1 0.359 24 33346.9 0.2965 1,493 587 4.63 2.819 48.2 0.366 25 184 45.6 0.2886 1,519 6064.53 2.657 37.1 0.362 26 95 46.3 0.2887 1,410 557 4.74 2.076 36.7 0.32827 37 48.0 0.2498 1,590 606 4.74 2.081 40.5 0.375

Growth Curves—FIG. 4 compares LVD for colts vs. fillies, and is typicalof sex-related differences. Most growth curves were described well(R²≧0.90) by second-degree polynomial equations, as shown on the graphs.The growth curves should be limited to application over the period from12 through 27 months of age for which they were calculated (i.e., notused to estimate average LVD at 32 months of age).

Anomalies appeared in the data patterns of cardiac measurements versusage at 20 and 21 months of age. These horses were primarily measuredduring October through December, between the timing of select yearlingand select two-year-old auctions. Horses often enter training duringthose interim months. Training regimens, and thus each heart's responseto training, likely varied greatly during this time (Young, 1999).Puberty may play a role among fillies at this age. Most horses weremeasured during this period at private farms, without any pre-selectionbased on conformation or pedigree. The ratio of colts to fillies (60%colts to 40% fillies) in this study closely matches those at auctions.This ratio may favor colts because breeding farms keep some of thebest-bred, best-conformed fillies for their breeding programs.Therefore, relative to auctions, the fillies seen at private farms maybe of higher quality, overall, since they may include the best-bred,best-conformed fillies that never make it to auctions.

Among the total population measured, generally, the bigger the horse,the bigger its heart, all else being equal. FIGS. 5-8 provide a visualoverview of the relationship between cardiac measurements and the weightof the horse. FIGS. 9-10 compare LVD and WEIGHT percentiles for highearners vs. low earners, and are typical of performance-relateddifferences (except for PS). Not only were future high earners heavierthan low earners, but, even when normalized by sex, age and weight, highearners still had higher cardiac measurements. Sample sizes of highearners in these graphs were small at 19 and 20 months of age.

Example 5 Statistical Overview of Cardiac Data—T-Tests

T-tests compared high vs. low earners of combined sexes and ages, usingdata normalized for sex, age and size. Significant differences(P-values≦0.0001) existed between high and low earners for all of thecardiac parameters listed in Table 9, except for PS. Stepwise analysis,as discussed in this paper, identified SW or SPLN, LVS and HTWT as themost significant discriminant variables when differentiating betweenhigh and low earners. High earners were defined as horses that raced atleast three times, with earnings per start of at least $10,000.

TABLE 9 T-tests - Percentiles (Data Adjusted for Age, Sex and Weight)High Earners (Earnings Per Start ≧ $10,000) vs. Low Earners (EarningsPer Start ≦ $2,000) LOW EARNERS HIGH EARNERS VARS n Mean SD n Mean SDP-Value LVD 1061 45.93 28.61 418 53.12 28.32 0.0000 LVS 1061 46.45 28.61418 52.72 28.43 0.0001 SW 1061 46.22 27.60 418 53.29 27.17 0.0000 PS1061 50.09 29.56 418 49.89 29.03 0.9050 SPLEEN 1025 42.78 22.99 40548.87 22.71 0.0000 WEIGHT 1091 47.25 29.40 424 60.11 27.38 0.0000 HEIGHT1091 53.47 28.58 424 65.81 26.07 0.0000 HTWT 1091 45.32 29.02 424 58.5327.24 0.0000

T-tests also compared high earner routers vs. high earner sprinters ofcombined sexes and ages, using data standardized for horses of the sameage, sex and size. Significant differences (P-values≦0.05) existedbetween high earner routers and sprinters for the cardiac variables ofLVD, LVS, WEIGHT, HEIGHT and HTWT, as shown in Table 10. Stepwiseanalysis, as discussed in this paper, identified LVD, LVS, HTWT and PSas the most significant discriminant variables when differentiatingbetween high earner routers and sprinters. High earner routers raced atleast three times at distances of at least 8.5 furlongs, with earningsper start at those route distances of at least $10,000. High earnersprinters raced at least three times at distances below seven furlongs,with earnings per start of at least $10,000 at those sprint distances.

TABLE 10 T-Tests - Percentiles (Data Adjusted for Age, Sex and Weight)High Earner Routers (Raced ≧ 8.5 Furlongs) vs. High Earner Sprinters(Raced < 7 Furlongs) SPRINTERS ROUTERS VARS n Mean SD n Mean SD P-ValueLVD 180 48.68 28.69 134 56.95 27.83 0.0110 LVS 180 47.68 28.31 134 58.1728.11 0.0012 SW 180 52.08 27.51 134 56.60 27.27 0.1495 PS 180 53.0429.31 134 47.79 27.55 0.1085 SPLEEN 176 47.38 22.84 128 50.04 23.240.3207 WEIGHT 180 55.10 26.99 134 64.12 24.11 0.0024 HEIGHT 180 59.9926.83 134 69.51 24.60 0.0014 HTWT 180 52.85 27.15 134 63.06 24.50 0.0007

Example 6 Statistical Overview of Cardiac Data—Standardizing CardiacMeasurements to Eliminate the Effects of Age Sex and Weight

The high correlation between age and size vs. most cardiac measurements(see Table 11) was not present among percentiles (see Table 12).Therefore, when looking at horses of different age, sex and size, it ispossible to compare their cardiac measurements by standardizing theirdata (i.e., using percentiles, as described on page 8). To measure thecorrelation between age and size vs. most cardiac measurements, Pearsoncorrelation coefficients (r) were computed between cardiac measurementsfor raw data and percentiles (standardized for sex, age and weight).Tests for significance of correlation coefficients producedP-Values<0.0001. Correlation coefficients were squared and multipliedtimes 100 to compute coefficients of determination (R2), as shown inTable 11-Table 12.

Essentially, due to the standardization of the data, where there was ahigh degree of correlation throughout the MONTHS column and bottom threerows (WEIGHT, HEIGHT and HTWT) of Table 11, there was little correlationshown in the same column and rows of Table 12 (see shaded areas).

TABLE 11 Coefficients of Determination (R²) (n ranged between7,288-7,434) Among Raw Data (Unadjusted for Sex, Age and Weight)

TABLE 12 Coefficients of Determination (R²) (n ranged from 7,288-7,434)Among Percentiles (Standardized for Sex, Age and Weight)

Example 7 Statistical Overview of Cardiac Data—Covariance Analysis ofMeans to Assess the Effects of Age and Sex on Cardiac Measurements

Analysis of covariance showed that age- and weight-adjusted means forcardiac measurements were significantly different (P-values≦0.01)between colts and fillies 12 through 27 months old, as shown in Table13.

TABLE 13 Means Adjusted for Age and Weight LS MEANS VARIABLES COLTSFILLIES P-VALUES N LVD 13,315 12,832 0.0001 7,434 LVS 4,318 4,179 0.00017,434 SW 53.86 52.12 0.0001 7,434 PS 67.55 67.41 0.0100 7,434 SPLEEN 193183 0.0001 7,220

Analysis of covariance showed that sex- and weight-adjusted means forcardiac measurements were sometimes significantly different betweenhorses of different months of age. The significance of differencesvaried depending on the variables studied and the number of monthsapart. In most cases, significant differences (P-values≦0.05) were rareor weak when comparing yearlings to yearlings, or two-year-olds totwo-year-olds, while differences were significant when comparingyearlings to two-year-olds.

Example 8 Stepwise Discriminant Analysis of the Relationship of CardiacMeasurements to Performance

It is impossible to know the level of ability of most horses measuredthat subsequently never raced, or raced just a couple of times. For thisreason, when forming groups of high vs. low earners or routers vs.sprinters, horses used had to have raced at least three times. Raisingthe minimum number of starts (up to 6) did not improve or weakendiscriminant analyses.

Stepwise analysis was conducted for colts, fillies and combined sexes,using percentiles for the variables: LVD, LVS, SW, PS, SPLN and HTWT(HTWT is the product of height times weight).

Stepwise analysis was used to identify statistically significantvariables that could differentiate between groups of horses categorizedas high and low earners, defined as:

-   -   High Earners. Raced at least three times, with earnings per        start of at least $10,000.    -   Low Earners. Raced at least three times, with earnings per start        of $2,000 or less.

Among the horses in this study that raced at least three times in NorthAmerica, 34 percent earned $2,000 or less per start (categorized as“low” earners) and 13 percent earned at least $10,000 per start(categorized as “high” earners). Table 2 provides average worldwideperformance statistics for the Thoroughbred breed.

For high vs. low earners, stepwise analysis identified the followingsignificant variables (listed in order of statistical significance):

-   -   Combined Sexes. HTWT, SW or SPLN, LVS    -   Colts. HTWT, SW or SPLN    -   Fillies. HTWT, SW or SPLN

Stepwise analysis was used to identify statistically significantvariables that could differentiate between groups of horses categorizedas high earner sprinters and high earner routers, defined as:

-   -   High Earner Sprinters. Raced at least 3 times at distances<7.0        furlongs, earned at least $10,000 per start at distances<7.0        furlongs, and earned less than $2,000 per start at distances≧8.5        furlongs.    -   High Earner Routers. Raced at least 3 times at distances≧8.5        furlongs, and earned at least $10,000 per start at distances≧8.5        furlongs.

For high earner sprinters vs. high earner routers, stepwise analysisidentified the following significant variables (listed in order ofstatistical significance):

-   -   Combined Sexes. HTWT, LVS    -   Colts. LVD, HTWT    -   Fillies. PS, HTWT

Example 9 Multivariate Discriminant Analysis of the Relationship ofMeasurements to Performance

Discriminant analysis was used to classify high earners vs. low earners,and high earner routers vs. high earner sprinters, as defined in thestepwise analysis section.

Discriminant results were based on a classification threshold of 50%. Aclassification threshold is the minimum acceptable probability (asdefined by the model user) required to classify a horse into aparticular group. Thus, no horse was classified into a group unless themodels assigned it at least a 50% probability of belonging to thatgroup. Generally, the higher the threshold, the better the modelsperformed (i.e., a horse with a 70% high earner probability was morelikely to be a high earner than a horse with a lower probability. As thethreshold increases for a particular group, the models generallymisclassify more members of that group. At public auctions, a high “highearner” threshold would minimize the chances of buying poor performers(Type II errors), while increasing the chances of rejecting goodperformers (Type I errors).

Z-statistics were computed to determine the reliability of discriminantresults using the formula below (shown for high earners):

$Z_{H} = \frac{P_{H_{post}} - P_{H_{pre}}}{\sqrt{\frac{P_{H_{pre}} \cdot ( {1 - P_{H_{pre}}} )}{N_{{CH}_{post}}}}}$

Where:

-   -   N_(Hpre)=Number of high earners in model    -   N_(Tpre)=Total number of horses in model    -   N_(HCCpost)=Number of high earners correctly classified by model    -   N_(CHpost)=Number of horses classified as high earners by model    -   P_(Hpre)=Pre-model probability (N_(Hpre)/N_(Tpre))    -   P_(Hpost)=Post-model probability (N_(Hccpost)/N_(CHpost))

P-values associated with the Z-statistics were reported in place ofZ-statistics (Table 14-Table 25).

The model parameters were:

-   -   Horses had to be born by 1997 (so would have racing data through        three-year-old year)    -   Horses had to have at least 3 starts (i.e., sound enough to race        multiple times)

Two types of discriminant analyses, called blind and non-blind tests,were conducted for each model.

Non-Blind Test. A non-blind test is one in which the horses classifiedby a model were used to create the model. Thus, the models “saw” thosehorses before. A non-blind test is the best-case scenario of how well amodel performs.

Blind Test. A blind-test is one in which the horses classified by amodel were not used to create the model. Thus, the models did not “see”those horses before.

Three tables were used to summarize each discriminant analysis in termsof blind and non-blind tests. The first table presents non-blind testresults based on all horses available for the study. The second tablepresents non-blind test results based on horses with names beginningwith the letters A-M. The third table presents blind-test results, forwhich the A-M model was used to classify horses with names beginningwith the letters N-Z, which the models hadn't seen previously. Eachtable presents summary statistics as described below:

Pre-Model Probability. Discriminating between two groups (A and B), thepre-model probability is the ratio of all Group A or Group B horses tothe total number of horses in the model. This is the probability, usinga random selection technique without statistically created models, ofcorrectly classifying a Group A or Group B horse. This probability isshown as a Ratio and a Percent. For example, if there are 7 Group Ahorses and 93 Group B horses, there is a 7% probability of randomlyselecting a Group A horse. For Group A horses, this would be shown as aratio of 7/100 and as a percent of 7.00.

Post-Model Probability. Discriminating between two groups (A and B) thepost-model probability is the ratio of Group A or Group B horsescorrectly classified by the models to the total number of horsesclassified by the statistically created models as Group A or Group Bhorses. This is the probability with discriminant models of correctlyclassifying Group A or Group B horses. Using the example above, adiscriminant model classifying the same 100 horses might classify 25horses into Group A, of which 5 horses actually belonged to Group A. Inthis case, the ratio for Group A horses would be 5/25, or 20 percent.Thus, in this example, the discriminant models improved the odds ofcorrectly identifying Group A horses from 7% without models to 20% withmodels. Likewise, they improved the odds of correctly classifying GroupB horses from 93% without models to 73/75, or 97.3% with models.

P-value. The P-value was listed corresponding to the Z-statisticcomputed for each model.

The variables HTWT, SW, and LVS, as identified by stepwise analysis,were used in the following high earner vs. low earner discriminantmodels, e.g., Tables 14-25. The predictive results of the blind andnon-blind tests were similar. Results showed that as long as data wasfirst standardized (using percentiles) for each subject's sex, age andsize, each subject's data could be compared with data from subjects ofdifferent sex, age and size. This made the combined sexes discriminantmodels just as powerful as separate colt and filly models.

Further comparisons of earnings groups, including $10,000+earnings perstart vs. less than $7,500-earnings per start produced similar results.Thus, the models, using the same independent variables, successfullydifferentiated between stakes- and allowance-caliber horses, as well asbetween stakes- and claiming-caliber horses.

Horses generally earned more and raced less frequently as theprobability of being high earners, as assigned by the discriminantmodel, increased.

Table 14-Table 16 summarize discriminant results for non-blind and blindtests of high earners and low earners, comprised of colts and filliescombined, that had raced at least three times (i.e., had three“starts”). High earners earned at least $10,000 per start and lowearners earned $2,000 or less per start. The improvement associated withdiscriminant modeling was statistically significant for both high andlow earners for all groups studied (P-values<0.0027).

Non-Blind A-Z. Table 14 shows that among 1,479 total horses, non-blinddiscriminant models improved the odds of correctly classifying highearners from 28.26% without models to 37.32% with models. They improvedthe odds of correctly classifying low earners from 71.74% without modelsto 79.57% with models. The improvement associated with discriminantmodeling was statistically significant for both high and low earners(P-values<0.0001).

TABLE 14 Discriminant Model Results - High Earners vs. Low Earners Non-Blind Tests -- Combined Sexes - Names Starting with Letters A-ZPre-Model Post-Model Probability Probability P- Category Ratio Pct.Ratio Pct. Value High Earners  418/1479 28.26 256/686 37.32 0.0000 LowEarners 1061/1479 71.74 631/793 79.57 0.0000

Non-Blind A-M. Table 15 shows that among horses with names beginningwith the letters A-M, non-blind discriminant models improved the odds ofcorrectly classifying high earners from 27.75% without models to 37.65%with models. They improved the odds of correctly classifying low earnersfrom 72.25% without models to 80.80% with models. The improvementassociated with discriminant modeling was statistically significant forboth high and low earners (P-values<0.0001).

TABLE 15 Discriminant Model Results - High Earners vs. Low Earners Non-Blind Tests -- Combined Sexes - Names Starting with Letters A-MPre-Model Post-Model Probability Probability P- Category Ratio Pct.Ratio Pct. Value High Earners 245/883 27.75 154/409 37.65 0.0000 LowEarners 638/883 72.25 383/474 80.80 0.0000

Blind N-Z. Table 16 shows that among horses with names beginning withthe letters N-Z, blind discriminant models based on the A-M horsesimproved the odds of correctly classifying high earners from 29.03%without models to 37.77% with models. They improved the odds ofcorrectly classifying low earners from 70.97% without models to 78.62%with models. The improvement associated with discriminant modeling wasstatistically significant for both high and low earners(P-values≦0.0027).

TABLE 16 Discriminant Model Results - High Earners vs. Low Earners BlindTest -- Combined Sexes - Names Starting with Letters N-Z Pre-ModelPost-Model Probability Probability P- Category Ratio Pct. Ratio Pct.Value High Earners 173/596 29.03 105/278 37.77 0.0013 Low Earners423/596 70.97 250/318 78.62 0.0027

Table 17-Table 19 summarize discriminant results for high vs. lowearners among colts. Table 17 shows that among 880 colts, non-blinddiscriminant models improved the odds of correctly classifying highearners from 26.70% without models to 34.96% with models. They improvedthe odds of correctly classifying low earners from 73.30% without modelsto 80.47% with models. The improvement associated with discriminantmodeling was statistically significant for both high and low earners(P-values≦0.0004).

TABLE 17 Discriminant Model Results - High Earners vs. Low EarnersNon-Blind Tests - Colts - Names Starting with Letters A-Z Pre-ModelPost-Model Probability Probability P- Category Ratio Pct. Ratio Pct.Value High Earners 235/880 26.70 143/409 34.96 0.0002 Low Earners645/880 73.30 379/471 80.47 0.0004

Non-Blind A-M. Table 18 shows that among colts with names beginning withthe letters A-M, non-blind discriminant models improved the odds ofcorrectly classifying high earners from 26.47% without models to 33.33%with models. They improved the odds of correctly classifying low earnersfrom 73.53% without models to 79.51% with models. The improvementassociated with discriminant modeling was statistically significant forboth high and low earners (P-values≦0.0226).

TABLE 18 Discriminant Model Results - High Earners vs. Low EarnersNon-Blind Tests - Colts - Names Starting with Letters A-M Pre-ModelPost-Model Probability Probability P- Category Ratio Pct. Ratio Pct.Value High Earners 140/529 26.47  82/246 33.33 0.0147 Low Earners389/529 73.53 225/283 79.51 0.0226

Blind N-Z. Table 19 shows that among colts with names beginning with theletters N-Z, blind discriminant models based on the A-M horses improvedthe odds of correctly classifying high earners from 27.07% withoutmodels to 38.41% with models. They improved the odds of correctlyclassifying low earners from 72.93% without models to 82.89% withmodels. The improvement associated with discriminant modeling wasstatistically significant for both high and low earners(P-values≦0.0022).

TABLE 19 Discriminant Model Results - High Earners vs. Low Earners BlindTest - Colts - Names Starting with Letters N-Z Pre-Model Post-ModelProbability Probability P- Category Ratio Pct. Ratio Pct. Value HighEarners  95/351 27.07  63/164 38.41 0.0011 Low Earners 256/351 72.93155/187 82.89 0.0022

Table 20-Table 22 summarize discriminant results for high vs. lowearners among fillies.

Non-Blind A-Z. Table 20 shows that among 599 fillies, non-blinddiscriminant models improved the odds of correctly classifying highearners from 30.55% without models to 42.22% with models. They improvedthe odds of correctly classifying low earners from 69.45% without modelsto 79.03% with models. The improvement associated with discriminantmodeling was statistically significant for both high and low earners(P-values≦0.0002).

TABLE 20 Discriminant Model Results - High Earners vs. Low EarnersNon-Blind Tests - Fillies - Names Starting with Letters A-Z Pre-ModelPost-Model Probability Probability P- Category Ratio Pct. Ratio Pct.Value High Earners 183/599 30.55 114/270 42.22 0.0000 Low Earners416/599 69.45 260/329 79.03 0.0002

Non-Blind A-M. Table 21 shows that among fillies with names beginningwith the letters A-M, non-blind discriminant models improved the odds ofcorrectly classifying high earners from 29.66% without models to 44.16%with models. They improved the odds of correctly classifying low earnersfrom 70.34% without models to 81.50% with models. The improvementassociated with discriminant modeling was statistically significant forboth high and low earners (P-values≦0.0005).

TABLE 21 Discriminant Model Results - High Earners vs. Low EarnersNon-Blind Tests - Fillies - Names Starting with Letters A-M Pre-ModelPost-Model Probability Probability P- Category Ratio Pct. Ratio Pct.Value High Earners 105/354 29.66  68/154 44.16 0.0001 Low Earners249/354 70.34 163/200 81.50 0.0005

Blind N-Z. Table 22 shows that among fillies with names beginning withthe letters N-Z, blind discriminant models based on the A-M horsesimproved the odds of correctly classifying high earners from 31.84%without models to 39.50% with models. They improved the odds ofcorrectly classifying low earners from 68.16% without models to 75.40%with models. The improvement associated with discriminant modeling wasnot statistically significant for high or low earners (P-values≦0.0819).

TABLE 22 Discriminant Model Results - High Earners vs. Low Earners BlindTest - Fillies - Names Starting with Letters N-Z Pre-Model Post-ModelProbability Probability P- Category Ratio Pct. Ratio Pct. Value HighEarners  78/245 31.84 47/119 39.50 0.0735 Low Earners 167/245 68.1695/126 75.40 0.0819

The variables HTWT and LVS, as identified by stepwise analysis, wereused in the high earner routers vs. sprinters discriminant models forcombined sexes (see Exhibits PM05290204 & PM05290205).

Table 23-Table 25 summarize discriminant results for high earner routersvs. sprinters. Table 23 shows that among 314 high earner horses,non-blind discriminant models improved the odds of correctly classifyingrouters from 42.68% without models to 55.03% with models. They improvedthe odds of correctly classifying sprinters from 57.32% without modelsto 68.48% with models. The improvement associated with discriminantmodeling was statistically significant for both routers and sprinters(P-values≦0.0037).

TABLE 23 Discriminant Model Results - High Earner Routers vs. HighEarner Sprinters Non-Blind Tests -- Combined Sexes -- Names Startingwith Letters A-Z Pre-Model Post-Model Probability Probability P-Category Ratio Pct. Ratio Pct. Value Routers 134/314 42.68  82/149 55.030.0023 Sprinters 180/314 57.32 113/165 68.48 0.0037

Non-Blind A-M. Table 24 shows that among high earner horses with namesbeginning with the letters A-M, non-blind discriminant models improvedthe odds of correctly classifying routers from 37.78% without models to51.85% with models. They improved the odds of correctly classifyingsprinters from 62.22% without models to 73.74% with models. Theimprovement associated with discriminant modeling was statisticallysignificant for both routers and sprinters (P-values≦0.0183).

TABLE 24 Discriminant Model Results - High Earner Routers vs. HighEarner Sprinters Non-Blind Tests -- Combined Sexes - Names Starting withLetters A-M Pre-Model Post-Model Probability Probability P- CategoryRatio Pct. Ratio Pct. Value Routers  68/180 37.78 42/81 51.85 0.0091Sprinters 112/180 62.22 73/99 73.74 0.0183

Blind N-Z. Table 25 shows that among high earner horses with namesbeginning with the letters N-Z, blind discriminant models based on theA-M horses improved the odds of correctly classifying routers from49.25% without models to 60.94% with models. They improved the odds ofcorrectly classifying sprinters from 50.75% without models to 61.43%with models. The improvement associated with discriminant modeling wasnot statistically significant for routers or sprinters(P-values≦0.0735).

TABLE 25 Discriminant Model Results - High Earner Routers vs. HighEarner Sprinters Blind Test - Combined Sexes - Names starting withLetters N-Z Pre-Model Post-Model Probability Probability Category RatioPct. Ratio Pct. P-Value Routers 66/134 49.25 39/64 60.94 0.0588Sprinters 68/134 50.75 43/70 61.43 0.0735

The variables HTWT, SPLEEN and LVS, as identified by stepwise analysis,were used in the following high earner vs. low earner discriminantmodels, e.g., Tables 26.

Table 26-Table 28 summarize discriminant results for non-blind and blindtests of high earners and low earners, comprised of colts and filliescombined, that had raced at least three times (i.e., had three“starts”). High earners earned at least $10,000 per start and lowearners earned $2,000 or less per start. The improvement associated withdiscriminant modeling was statistically significant for both high andlow earners for all groups studied (P-values≦0.0002).

Non-Blind A-Z. Table 26 shows that among 1,430 total horses, non-blinddiscriminant models improved the odds of correctly classifying highearners from 28.32% without models to 37.78% with models. They improvedthe odds of correctly classifying low earners from 71.68% without modelsto 79.95% with models. The improvement associated with discriminantmodeling was statistically significant for both high and low earners(P-values<0.0001).

TABLE 26 Discriminant Model Results - High Earners vs. Low EarnersNon-Blind Tests - Combined Sexes - Names Starting with Letters A-ZPre-Model Post-Model Probability Probability Category Ratio Pct. RatioPct. P-Value High Earners  405/1430 28.32 252/667 37.78 0.0000 LowEarners 1025/1430 71.68 610/763 79.95 0.0000

Non-Blind A-M. Table 27 shows that among horses with names beginningwith the letters A-M, non-blind discriminant models improved the odds ofcorrectly classifying high earners from 27.87% without models to 37.47%with models. They improved the odds of correctly classifying low earnersfrom 72.13% without models to 80.39% with models. The improvementassociated with discriminant modeling was statistically significant forboth high and low earners (P-values≦0.0001).

TABLE 27 Discriminant Model Results - High Earners vs. Low EarnersNon-Blind Tests - Combined Sexes - Names Starting with Letters A-MPre-Model Post-Model Probability Probability Category Ratio Pct. RatioPct. P-Value High Earners 238/854 27.87 148/395 37.47 0.0000 Low Earners616/854 72.13 369/459 80.39 0.0001

Blind N-Z. Table 28 shows that among horses with names beginning withthe letters N-Z, blind discriminant models based on the A-M horsesimproved the odds of correctly classifying high earners from 28.99%without models to 38.21% with models. They improved the odds ofcorrectly classifying low earners from 71.01% without models to 79.73%with models. The improvement associated with discriminant modeling wasstatistically significant for both high and low earners(P-values≦0.0009).

TABLE 28 Discriminant Model Results - High Earners vs. Low Earners BlindTest - Combined Sexes - Names Starting with Letters N-Z Pre-ModelPost-Model Probability Probability Category Ratio Pct. Ratio Pct.P-Value High Earners 167/576 28.99 107/280 38.21 0.0007 Low Earners409/576 71.01 236/296 79.73 0.0009

Colts

Table 29-Table 31 summarize discriminant results for high vs. lowearners among colts.

Non-Blind A-Z. Table 29 shows that among 859 colts, non-blinddiscriminant models improved the odds of correctly classifying highearners from 26.66% without models to 34.89% with models. They improvedthe odds of correctly classifying low earners from 73.34% without modelsto 80.75% with models. The improvement associated with discriminantmodeling was statistically significant for both high and low earners(P-values≦0.0004).

TABLE 29 Discriminant Model Results - High Earners vs. Low EarnersNon-Blind Tests - Colts - Names Starting with Letters A-Z Pre-ModelPost-Model Probability Probability Category Ratio Pct. Ratio Pct.P-Value High Earners 229/859 26.70 142/407 34.89 0.0002 Low Earners630/859 73.34 365/452 80.75 0.0004

Non-Blind A-M. Table 30 shows that among colts with names beginning withthe letters A-M, non-blind discriminant models improved the odds ofcorrectly classifying high earners from 26.45% without models to 34.58%with models. They improved the odds of correctly classifying low earnersfrom 73.55% without models to 80.58% with models. The improvementassociated with discriminant modeling was statistically significant forboth high and low earners (P-values≦0.0078).

TABLE 30 Discriminant Model Results - High Earners vs. Low EarnersNon-Blind Tests - Colts - Names Starting with Letters A-M Pre-ModelPost-Model Probability Probability Category Ratio Pct. Ratio Pct.P-Value High Earners 137/518 26.45  83/240 34.58 0.0042 Low Earners381/518 73.55 224/278 80.58 0.0078

Blind N-Z. Table 31 shows that among colts with names beginning with theletters N-Z, blind discriminant models based on the A-M horses improvedthe odds of correctly classifying high earners from 26.98% withoutmodels to 36.65% with models. They improved the odds of correctlyclassifying low earners from 73.02% without models to 81.67% withmodels. The improvement associated with discriminant modeling wasstatistically significant for both high and low earners(P-values≦0.0091).

TABLE 31 Discriminant Model Results - High Earners vs. Low Earners BlindTest - Colts - Names Starting with Letters N-Z Pre-Model Post-ModelProbability Probability Category Ratio Pct. Ratio Pct. P-Value HighEarners  92/341 26.98  59/161 36.65 0.0058 Low Earners 249/341 73.02147/180 81.67 0.0091

Fillies

Table 32-Table 34 summarize discriminant results for high vs. lowearners among fillies.

Non-Blind A-Z. Table 32 shows that among 571 fillies, non-blinddiscriminant models improved the odds of correctly classifying highearners from 30.82% without models to 42.01% with models. They improvedthe odds of correctly classifying low earners from 69.18% without modelsto 79.14% with models. The improvement associated with discriminantmodeling was statistically significant for both high and low earners(P-values≦0.0002).

TABLE 32 Discriminant Model Results - High Earners vs. Low EarnersNon-Blind Tests - Fillies - Names Starting with Letters A-Z Pre-ModelPost-Model Probability Probability Category Ratio Pct. Ratio Pct.P-Value High Earners 176/571 30.82 113/269 42.01 0.0001 Low Earners395/571 69.18 239/302 79.14 0.0002

Non-Blind A-M. Table 33 shows that among fillies with names beginningwith the letters A-M, non-blind discriminant models improved the odds ofcorrectly classifying high earners from 30.06% without models to 43.05%with models. They improved the odds of correctly classifying low earnersfrom 69.94% without models to 80.54% with models. The improvementassociated with discriminant modeling was statistically significant forboth high and low earners (P-values≦0.0017).

TABLE 33 Discriminant Model Results - High Earners vs. Low EarnersNon-Blind Tests - Fillies - Names Starting with Letters A-M Pre-ModelPost-Model Probability Probability Category Ratio Pct. Ratio Pct.P-Value High Earners 101/336 30.06  65/151 43.05 0.0005 Low Earners235/336 69.94 149/185 80.54 0.0017

Blind N-Z. Table 34 shows that among fillies with names beginning withthe letters N-Z, blind discriminant models based on the A-M horsesimproved the odds of correctly classifying high earners from 31.91%without models to 40.34% with models. They improved the odds ofcorrectly classifying low earners from 68.09% without models to 76.72%with models. The improvement associated with discriminant modeling wasstatistically significant for both high and low earners(P-values≦0.0488).

TABLE 34 Discriminant Model Results - High Earners vs. Low Earners BlindTest - Fillies - Names Starting with Letters N-Z Pre-Model Post-ModelProbability Probability Category Ratio Pct. Ratio Pct. P-Value HighEarners  75/235 31.91 48/119 40.34 0.0488 Low Earners 160/235 68.0989/116 76.72 0.0455

Example 10 Chi-Square Analysis of Performance vs. Heart Size andPhysical Size

The statistical methods described to this point, and which have shownthe predictive nature of cardiac measurements, are perhaps lessintuitive than the following examples. Once the key variables of HTWT(the product of height times weight—used as a measure of physical size),LVD, LVS, PS, SPLN, and SW were standardized for age, sex and weight, ona scale from 0 (small) to 100 (large), groups of horses based on thesevariables could be created. For example, groups of horses could becreated with above or below average LVD, or horses could be grouped intoquartiles (i.e., from the bottom 25% to the top 25%) based on specificheart measurements or physical size. Questions such as: “Was there ashigh a percentage of high earners among horses with below average LVD asamong horses with above average LVD?” could then be answered.

Table 35 shows the percentage of horses that earned at least $10,000 perracing start among horses grouped by physical size and heart size.Overall, 13.3 percent of the horses in this study's sample earned atleast $10,000 per start.

TABLE 35 Percentage of Horses that Earned at least $10,000 Per StartBased on Percentiles for Individual Variables Percentiles 0-25% 25-50%50-75% 75-100% HTWT 7.6 12.8 14.5 17.8 LVD 11.6 11.1 13.4 17.5 LVS 11.411.8 13.9 16.3 SW 10.8 13.1 13.1 16.3 PS 14.3 11.4 14.0 13.3 Average*10.4 12.2 13.7 17.0 *Average was calculated excluding PS, which wasn'tusually predictive.

Table 35 shows that as physical size and heart size measurementsincreased, except for PS, so did the percentage of high earners. Thistable shows that 17.8% of horses with HTWT in the 75-100% percentilerange earned at least $10,000 per start. The percentage of horses thatearned at least $10,000 per start was below average (13.3% was averagefor all horses studied) for groups with cardiac variables below the50^(th) percentile. Horses with cardiac variables in the 75^(th) andhigher percentiles were more likely to earn at least $10,000 per start.

Next, horses were first grouped by physical size, and then by heartmeasurement size. Table 36 shows that all groups of horses with HTWTpercentiles of 75-100% (right-hand column) produced higher than averagepercentages of horses with earnings per start (EPS)≧$10,000. All groupsof horses with HTWT percentiles of 0-25% (left-hand column) producedfewer than average percentages of horses with EPS≧$10,000, regardless ofheart measurement size.

Shaded areas in Table 36 show groups with higher than averagepercentages of horses with EPS≧$10,000. Horses with HTWT percentiles inthe 25-50% range generally performed as well as average as long ascardiac variables were above average.

The highest percentages of high earners occurred when percentiles forboth HTWT and heart size were at least 75%. In cases where HTWT andheart size percentiles were at least 75%, the average percentage ofhorses with EPS≧$10,000 was 23.0% (excluding PS)—a 73% improvement overrandom odds of selecting high earners (13.3% vs. 23.0%).

TABLE 36 Percentage of Horses that Earned at least $10,000 Per StartBased on Percentiles for Individual Cardiac Variables Combined with HTWT

Above average performance categories are shaded.

Chi-square analysis was used to examine how Thoroughbreds' normalizedheart size (as measured by LVD, LVS, PS, and SW) and normalized physicalsize (as measured by HTWT, which is the product of height times weight)relate to subsequent earnings and racing distances. Chi-square methodswere used to show the predictive nature of each variable individually.Chi-square methods were then used to show the predictive nature of eachcardiac variable, when used in conjunction with HTWT.

High earners and high earner routers were more likely to be aboveaverage in normalized physical size and normalized heart size (asmeasured by LVD, LVS, and SW). Low earners were more likely to be belowaverage in normalized physical size and normalized heart size. Highearner sprinters tended to be above average in normalized physical sizewith thick heart walls (as measured by normalized SW).

Statistics describing these relationships were summarized in tables37-52.

Extremely high earners—Among 3,150 horses that raced at least threetimes by the end of their three-year-old year, 101 (3.2%) earned atleast $250,000 and had earnings per start of at least $20,000. Thefollowing tables show the percentage of extremely high earners withvarious combinations of above and below average normalized HTWT andnormalized cardiac measurements (LVD, LVS, SW and PS).

The following tables, Tables 37-40, show that a disproportionately highpercentage of extremely high earners were large physically (for theirsex, and chronological age), and had large hearts even relative to otherlarge horses, i.e., when cardiac measurement variables were normalizedfor sex, chronological age, and physical size. Extremely high earnerswere three times more likely to have above average normalized HTWT andnormalized cardiac measurements than to have below average normalizedHTWT and normalized cardiac measurements. When breaking normalized HTWTcategories down further, 4% of extremely high earners had HTWT of 0-25%,while 38% had HTWT of 75-100%—a nearly ten-fold difference. The generalpopulation, e.g., when not looking at racing performance successvariables, is fairly evenly distributed among the four quartiles listedin the tables.

TABLE 37 HTWT Below Average Above Average LVD Below Average 17% 19%Above Average 15% 50%

TABLE 38 HTWT Below Average Above Average SW Below Average 15% 23% AboveAverage 17% 46%

TABLE 39 HTWT Below Average Above Average LVS Below Average 18% 24%Above Average 14% 45%

TABLE 40 HTWT Below Average Above Average PS Below Average 12% 31% AboveAverage 20% 38%

The following tables, Table 41-Table 44, show the percentage of highearner routers with various combinations of above and below averagenormalized HTWT and normalized cardiac measurements (LVD, LVS, SW andPS).

These tables show that a disproportionately high percentage of highearner routers were large physically (compared to other subjects of thesame sex and chronological age), and had large hearts even relative toother large horses, i.e., when normalized for sex, chronological age,height and weight. High earner routers were four times more likely tohave above average normalized HTWT and normalized cardiac measurementsthan to have below average normalized HTWT and normalized cardiacmeasurements. The general population is fairly evenly distributed amongthe four quartiles listed in the tables when not considering the racingperformance variables.

TABLE 41 HTWT Below Average Above Average LVD Below Average 12% 25%Above Average 15% 48%

TABLE 42 HTWT Below Average Above Average SW Below Average 10% 31% AboveAverage 16% 43%

TABLE 43 HTWT Below Average Above Average LVS Below Average 13% 26%Above Average 14% 47%

TABLE 44 HTWT Below Average Above Average PS Below Average 12% 37% AboveAverage 14% 37%

The following tables, Tables 45-48, show the percentage of high earnersprinters with various combinations of above and below averagenormalized HTWT and normalized cardiac measurements (LVD, LVS, SW andPS).

These tables show that high earner sprinters were fairly evenlydistributed by normalized physical size and the two normalized heartsize variables of LVD and LVS, especially compared to distributions ofthe same variables for high earner routers. However, the tables showthat high earner sprinters were about 50% more likely to have been bigphysically (normalized HTWT) with above average normalized SW and/or PS,than to be small physically, with small SW and/or PS. High earnersprinters were most likely to be relatively big horses with thick heartwalls (normalized SW). The general population, i.e., all levels ofracing performance, and not just sprinters or high earner sprinters, isfairly evenly distributed among the four quartiles listed in the tables.

TABLE 45 HTWT Below Average Above Average LVD Below Average 22% 27%Above Average 24% 26%

TABLE 46 HTWT Below Average Above Average SW Below Average 22% 22% AboveAverage 25% 32%

TABLE 47 HTWT Below Average Above Average LVS Below Average 23% 28%Above Average 24% 26%

TABLE 48 HTWT Below Average Above Average PS Below Average 19% 23% AboveAverage 28% 31%

The following tables, Table 49-52 show the percentage of low earnerswith various combinations of above and below average normalized HTWT andnormalized cardiac measurements (LVD, LVS, SW and PS).

These tables show that a disproportionately high percentage of lowearners were relatively small physically, and had small hearts evenrelative to other small horses. Low earners were about 1.5 times morelikely to have below average normalized HTWT and normalized cardiacmeasurements than to have above average normalized HTWT and normalizedcardiac measurements. The general population is fairly evenlydistributed among the four quartiles listed in the tables when notconsidering subsets of different levels of racing performance.

TABLE 49 HTWT Below Average Above Average LVD Below Average 31% 23%Above Average 25% 20%

TABLE 50 HTWT Below Average Above Average SW Below Average 31% 23% AboveAverage 25% 20%

TABLE 51 HTWT Below Average Above Average LVS Below Average 32% 23%Above Average 24% 20%

TABLE 52 HTWT Below Average Above Average PS Below Average 28% 21% AboveAverage 29% 22%

Example 11 Predicting Racing Performance

Discriminant results showed that a horse's weight and height wereimportant predictive indices of subsequent performance, in terms ofearnings and successful distances raced. Additionally, interventricularseptal wall structural thickness (SW) as defined in FIG. 3, orcross-sectional spleen area (SPLN), were the most important predictivevariable when differentiating between high and low earners. In additionto physical size, the left ventricle in diastole and systole (LVD andLVS) were the most important predictive variables when differentiatingbetween successful sprinters and routers.

Several of the variables studied were highly correlated (i.e., similar).Discriminant models typically had very similar results when one or twovariables were replaced with other variables with which they were highlycorrelated (e.g. LVS and LVD, or WT and HTWT).

In most cases, combined-sex discriminant models correctly identified thesame horses that were correctly identified by the same-sex models.

Blind tests showed that cardiac parameters predicted subsequent racingperformance with far greater accuracy than possible selecting horsesfrom these groups at random. Models successfully differentiated not onlybetween stakes- and claiming-caliber horses, but also between stakes-and allowance-caliber horses.

On average, blind test discriminant models improved random odds ofidentifying high earners (or routers) by 35 percent (i.e., going from a30% probability of correctly identifying high earners without models toa 40% probability with models).

Stepwise and discriminant analyses beyond those presented here sometimesproduced exceptional results for one group in the comparison, butunexceptional results for the other group. For example, a high vs. lowearners model may accurately predict high earners, while just meetingrandom expectations among low earners. Multiple models differentiated bylevel of earnings may be needed in such instances. Model limitationshave to be assessed relative to potential applications. Z-tests werehelpful in determining the statistical strength of discriminant resultsfor each individual group represented in the models.

Example 12 Using Subjective Visual Cardiac Parameters to Predict RacingPerformance

Subjective ratings (ranging from 1=poor to 5=excellent) to describe theimages on the ultrasound machine—visual impressions of ecogenicity(e.g., clarity, sharpness of contrast, type and symmetry of shapes,smoothness of functioning of structures) of the 2D images were recorded.These ratings were recorded as: Ecogenicity (EC and VEC); general shapeof the image at diastole and systole (CATE and SQ); clarity andsharpness of contrast of left ventricle during diastole and systole (DCLand SCL); smoothness of left ventricle during diastole and systole (DSMand SSM); blood backflow from left ventricle during diastole and systole(DBF and SBF); double-beat wave (XB); overall irregularity of the heartimage (IRRG); how well the valve closes (NVC); and overall clearness ofimage in diastole (PVAR).

Stepwise analysis identified statistically significant variables thatcould differentiate between groups of horses categorized as high and lowearners.

The variables considered in the analysis were LVD, LVS, SW, PS, HTWT,EC, CATE, DCL, DSM, DBF, XB, VEC, SQ, SCL, SSM, SBF, IRRG, NVC, andPVAR. Among these variables, LVD, LVS, SW, PS were standardized for sex,age and weight, and HTWT was standardized for sex and age.

For high vs. low earners, with the additional consideration of visualratings as described above, stepwise analysis identified the followingsignificant variables

-   -   Combined Sexes. HTWT, PVAR, SBF    -   Colts. SBF, HTWT, DSM    -   Fillies. HTWT, PVAR, SQ, DSM

In order to work with higher numbers of horses for discriminant analysesusing the subjective visual variables (assessed each on a scale from 1to 5), horses for which there were only two-year-old race records wereadded to the groups of raced horses used elsewhere to assess racingperformance levels in this study. These were horses born in 1998. Thus,unlike everywhere else in this monograph, this analysis of raced horseshad some horses with two- and three-year-old race records and otherswith just two-year-old race records.

The variables used in discriminant analysis were those identified assignificant by stepwise analysis. Only combined sex models were analyzeddue to limited number of horses.

Non-Blind A-Z. Table 53 shows that among 394 horses, non-blinddiscriminant models improved the odds of correctly classifying highearners from 33.25% without models to 43.93% with models. They improvedthe odds of correctly classifying low earners from 66.75% without modelsto 75.11% with models. All results were statistically significant(P-values≦0.0083).

TABLE 53 Discriminant Model Results Using Subjective 1-5 Variables -High vs. Low Earners Non-Blind Tests -- Combined Sexes - Names Startingwith Letters A-Z Pre-Model Post-Model Probability Probability CategoryRatio Pct. Ratio Pct. P-Value High Earners 131/394 33.25  76/173 43.930.0029 Low Earners 263/394 66.75 166/221 75.11 0.0083

Non-Blind A-M. Table 54 shows that among horses with names beginningwith the letters A-M, non-blind discriminant models improved the odds ofcorrectly classifying high earners from 34.18% without models to 41.28%with models. They improved the odds of correctly classifying low earnersfrom 65.82% without models to 71.88% with models. Results were notstatistically significant (P≦0.1499).

TABLE 54 Discriminant Model Results Using Subjective 1-5 Variables -High vs. Low Earners Non-Blind Tests -- Combined Sexes - Names Startingwith Letters A-M Pre-Model Post-Model Probability Probability CategoryRatio Pct. Ratio Pct. P-Value High Earners  81/237 34.18 45/109 41.280.1188 Low Earners 156/237 65.82 92/128 71.88 0.1499

Blind N-Z. Table 55 shows that among horses with names beginning withthe letters N-Z, blind discriminant models based on the A-M horsesimproved the odds of correctly classifying high earners from 31.85%without models to 43.42% with models. They improved the odds ofcorrectly classifying low earners from 68.15% without models to 79.01%with models. All results were statistically significant(P-values≦0.0444).

TABLE 55 Discriminant Model Results Using Subjective 1-5 Variables -High vs. Low Earners Blind Test -- Combined Sexes - Names Starting withLetters N-Z Pre-Model Post-Model Probability Probability Category RatioPct. Ratio Pct. P-Value High Earners  50/157 31.85 33/76 43.42 0.0300Low Earners 107/157 68.15 64/81 79.01 0.0444

What is claimed:
 1. A method of selecting an unraced racehorse candidatehaving a better than average likelihood of becoming a high earner, saidmethod comprising: (i) measuring the width of the ventricular septalwall of said racehorse candidate utilizing an ultrasound machine; (ii)comparing said measurement to a collection ofultrasonographically-obtained measurements from a group of horses,wherein said collection of measurements comprises ventricular septalwall width measurements for at least about 75 horses of about the sameage, sex, and weight as said racehorse candidate; and (iii) selectingsaid racehorse candidate if it has an ultrasonographically-obtainedventricular septal wall width measurement that is greater than the meanultrasonographically-obtained ventricular septal wall width measurementfrom said collection of measurements.
 2. The method of claim 1, whereinsaid unraced racehorse candidate is selected if it has a ventricularseptal wall width that is in the 75th percentile or higher when comparedto the ventricular septal wall width measurements from said collectionof measurements.
 3. The method of claim 1, wherein said unracedracehorse is available for sale at an auction.
 4. The method of claim 1,further comprising the step of ultrasonographically measuring thecross-sectional area of the left ventricle in diastole of said unracedracehorse candidate; wherein said collection of measurements furthercomprises ultrasonographically-obtained left ventricle in diastolecross-sectional area measurements for at least about 75 horses of aboutthe same age, sex, and weight as said unraced racehorse candidate. 5.The method of claim 4, wherein said unraced racehorse candidate isselected if it has a ventricular septal wall width and left ventricle indiastole cross sectional area that is greater than the mean ventricularseptal wall width and left ventricle in diastole cross-sectional areameasurement from said collection of measurements.
 6. The method of claim4, wherein said unraced racehorse candidate is selected if it has aventricular septal wall width and a left ventricle in diastole crosssectional area measurement that is in the 75th percentile or higher whencompared to the ventricular septal wall width and left ventricle indiastole cross sectional area measurements from said collection ofmeasurements.
 7. The method of claim 1, wherein said ventricular septalwall is situated between a left ventricle and a right ventricle, saidleft ventricle having a free wall and at least one moderator bandextending between said ventricular septal wall and said free wall, saidright ventricle having a free wall having an endocardial edge, saidright ventricular free wall terminating at a junction with aninterventricular septum, and wherein said measuring step comprisesultrasonographically measuring, in a left parasternal short-axis viewobtained at end diastole, the distance from the endocardial edge of theright ventricular free wall, at the point where the wall meets theinterventricular septum, through the interventricular septum, to thepoint of attachment of the moderator band to the ventricular septal wallin the left ventricle.
 8. The method of claim 1, wherein said measuringstep comprises ultrasonographically obtaining a left parasternal shortaxis echocardiogram of the left ventricle of said unraced racehorsecandidate.
 9. The method of claim 4, wherein said step ofultrasonographically measuring the left ventricle in diastole crosssectional area comprises measuring the circumference of the leftventricular chamber.
 10. The method of claim 4, wherein said step ofultrasonographically measuring the left ventricle in diastole crosssectional area measurement comprises obtaining a left parasternalshort-axis echocardiogram of the left ventricle of said racehorse. 11.The method of claim 1, the method further comprising the step ofultrasonographically measuring the cross-sectional area of the leftventricle in systole of said unraced racehorse candidate; wherein saidcollection of measurements further comprisesultrasonographically-obtained left ventricle in systole cross-sectionalarea measurements of at least about 75 horses of about the same age,sex, and weight as said racehorse candidate.
 12. The method of claim 11,wherein said unraced racehorse candidate is selected if it has aventricular septal wall width and left ventricle in systole crosssectional area that is greater than the mean ventricular septal wallwidth and left ventricle in systole cross-sectional area measurementfrom said collection of measurements.
 13. The method of claim 11,wherein said unraced racehorse candidate is selected if it has aventricular septal wall width and a left ventricle in systole crosssectional area measurement that is in the 75th percentile or higher whencompared to the ventricular septal wall width and left ventricle insystole cross sectional area measurements from said collection ofmeasurements.
 14. The method of claim 1, further comprising the steps ofultrasonographically measuring the cross-sectional area of the spleen ofsaid unraced racehorse candidate; wherein said collection ofmeasurements further comprises ultrasonographically-obtained spleniccross-sectional area measurements of at least about 75 horses of aboutthe same age, sex, and weight as said racehorse candidate.
 15. Themethod of claim 14, wherein said unraced racehorse candidate is selectedif it has a ventricular septal wall width and splenic cross sectionalarea that is greater than the mean ventricular septal wall width andsplenic cross-sectional area measurement from said collection ofmeasurements.
 16. The method of claim 14, wherein said unraced racehorsecandidate is selected if it has a ventricular septal wall width and asplenic cross sectional area measurement that is in the 75th percentileor higher when compared to the ventricular septal wall width and spleniccross sectional area measurements from said collection of measurements.17. The method of claim 1, the method further comprising the steps ofobtaining a measurement of the height times weight of said unracedracehorse candidate; wherein said collection of measurements furthercomprises height times weight measurements from at least about 75 horsesof about the same age and sex as said racehorse candidate.
 18. Themethod of claim 17, wherein said unraced racehorse candidate is selectedif both the ventricular septal wall width and the height times weightmeasurement are greater than the mean ventricular septal wall width andheight X weight measurements from said collection of measurements. 19.The method of claim 17, further comprising the step of selecting saidunraced racehorse candidate if it has both a ventricular septal wallwidth and a height times weight measurement that is in the 75thpercentile or higher when compared to the ventricular septal wall widthand height and weight measurements from said collection of measurements.20. The method of claim 17, the method further comprising the steps ofultrasonographically measuring the cross-sectional area of the leftventricle in systole of said unraced racehorse candidate; wherein saidcollection of measurements further comprisesultrasonographically-obtained left ventricle in systole cross-sectionalarea measurements from at least about 75 horses of about the same age,sex, and weight as said racehorse candidate.
 21. The method of claim 20,wherein said unraced racehorse candidate is selected if it has aventricular septal wall width, a left ventricle in systole crosssectional area, and a height times weight measurement that is greaterthan the mean ventricular septal wall width, left ventricle in systolecross sectional area, and height times weight measurements from saidcollection of measurements.
 22. The method of claim 20, wherein saidunraced racehorse candidate is selected if it has a ventricular septalwall width, a left ventricle in systole cross sectional area, and aheight times weight measurement that is in the 75th percentile or higherwhen compared to corresponding measurements from said collection ofmeasurements.
 23. The method of claim 1, wherein said unraced racehorsecandidate is a yearling or two year old.
 24. The method of claim 1, themethod further comprising the steps of: (iv) ultrasonographicallymeasuring one or more of the cross-sectional area of the left ventriclein systole, the cross-sectional area of the left ventricle in diastole,or the percent change in ventricular area per stroke of said unracedracehorse candidate; (v) obtaining a measurement of the height timesweight of said unraced racehorse candidate; (vi) comparing saidmeasurements from said unraced racehorse candidate to a collection ofmeasurements from a group of horses, wherein said collection ofmeasurements comprises height times weight measurements and one or moreof ultrasonographically-obtained cross-sectional area of the leftventricle in systole measurements, cross-sectional area of the leftventricle in diastole measurements, or percent change in ventriculararea per stroke measurements from at least about 75 horses of the sameage, weight and sex as said racehorse candidate.
 25. The method of claim1, the method further comprising the step of: (iv) echocardiographicallyimaging the heart of said racehorse utilizing an ultrasound machine; (v)rating the image according to at least one cardiac parameter selectedfrom the group consisting of the general shape of the heart at diastoleand systole, the clarity and sharpness of contrast of left ventricleduring diastole and systole, the smoothness of the left ventricle duringdiastole and systole, blood backflow from the left ventricle duringdiastole and systole, valve closure, and clarity of the image indiastole; and (vi) comparing the rating to a collection of ratings ofthe same ultrasonographically-obtained cardiac parameter from a group ofhorses of about the same age, sex, and weight of said racehorsecandidate.